The present invention relates to toothbrushes, and more particularly, to toothbrushes having a particular combination of bristle tuft flexibility, density, angles and trim to provide enhanced conformity to the topography of the teeth for better cleaning thereof.
The primary purpose of toothbrushes is to clean the teeth by removing plaque and debris from the tooth surfaces, including the curved outer tooth surfaces and the interproximal surfaces between the teeth, i.e. the topography of the teeth. To facilitate such cleaning, conventional toothbrushes comprise generally uniform length tufts of bristles, a flat bristle trim, each bristle having an end which is held captive in and fixed to a brush head, and an end which is free and which is used for brushing. Toothbrushes having such a generally flat bristle trim are limited in their ability to conform to the curved surfaces of each tooth or to penetrate into the interproximal areas between the teeth.
The desire of users to cause brushes having such generally flat bristle trims to conform to the curved teeth and to penetrate into and reach the interproximal tooth surfaces is expressed by the forceful application of the brush to adequately deform the bristles to the topography of the teeth. Such forceful application of the brush deleteriously leads to excessive wear and irritation of gums without adequate conformation of the brush about and between the teeth to provide the desired cleaning.
U.S. Pat. No. 5,742,972 discloses a toothbrush having a bristle trim containing at the toe region of the head, furthest from the handle, a ramping down subset of bristle tufts with the longest bristle tuft adjacent to the toe. Along the heel region of the head, closest to the handle, is a series of bristle rows wherein any transverse cross-section of which is concave in shape, i.e. the bristle tufts along each side of the brush being longer than those closer to the center of the brush. This combination of tufts is designed to provide enhanced interproximal and gingival margin cleaning by better conforming to the curved surfaces of and between the teeth. While this combination of tufts does provide better conformity to the topography of the dentiture than a conventional uniform length, flat trim toothbrush; it does not have the diversity of tufts and trim necessary to provide the enhanced cleaning desired.
Alternately, U.S. Pat. Nos. 5,335,389, 5,341,537, 5,446,940 and U.S. Pat. No. Des. 352,396 disclose various other toothbrushes containing a combination of longer and shorter bristle tufts and bristle bars, which are orthogonal and acutely angled to the face of the disclosed toothbrushes. As in the case of U.S. Pat. No. 5,742,972, these toothbrushes will better conform to the curved surfaces of the teeth than conventional flat trim toothbrushes; but, also as in the case of U.S. Pat. No. 5,742,972, they do not have the diversity of bristle tufts and trim to provide the enhanced cleaning desired.
PCT International Publication WO 99/23910 discloses a toothbrush with a greater diversity of tufts, i.e. five (5) different bristle tufts, including a first enlarged tuft located at the toe of the toothbrush with a cross-sectional area of about 0.0373 square inches (0.241 cm2). This enlarged tuft is composed of uniform, flat trimmed, 0.440 inch (11.176 mm) long bristles which are densely packed and this enlarged tuft is angled forward to extend over the toe of the toothbrush. The other disclosed bristle tufts are arranged substantially in three columns along the balance of the brush head, each column containing about 10 rows of alternating length tufts. The two peripheral columns, along each side of the head, contain 0.350 inch (8.890 mm) long, round cross-section tufts, which are 0.0027 sq. inches (0.0174 cm2) in cross-sectional area; alternating with 0.440 inch (11.176 mm) long rectangular tufts, 0.0045 sq. inches (0.029 cm2) in cross-sectional area. The center column contains 0.440 inch (11.176 mm) long, 0.0045 sq. inch (0.029 cm2) rectangular tufts alternating with shorter, 0.350 inch (8.890 mm) long, 0.0084 sq. inch (0.0542 cm2) rectangular tufts. As disclosed in U.S. Pat. No. 5,511,275, a bristle tuft""s stiffness is directly proportional to the number of bristles in that tuft and to the density of the packing, i.e. a buttressing factor. The large, 0.0373 (0.241 cm2) and 0.0084 square inch (0.0542 cm2), densely packed, uniform flat trimmed bristle tufts disclosed in WO 99/23910 will exhibit significant buttressing and stiffness as described in U.S. Pat. No. 5,511,275, reducing the brushes ability to conform to the curved surfaces of the teeth without deleterious, excessive forceful application of the toothbrush by the user.
There is a need in the art for a toothbrush having a diversity of tufts, including curved bristle trim and wherein the bristle tufts better conform to the curvature of the teeth to provide enhanced cleaning without the need for deleterious, excessive brushing force by the user.
The present invention comprises a toothbrush with an elongated head connected to an elongated handle, which head has a first and a second grouping of flexible bristle tufts extending therefrom, both groupings have trim patterns containing at least one radius of curvature to provide enhanced conformity to the curvature of the teeth; the first grouping, located nearer the toe of the brush head, contains bristle tufts angled slightly towards the toe of the toothbrush, and wherein the bristle tufts are relatively more densely packed, providing a combination of features which provides the flexibility and configuration of bristle tufts to conform to the curvature of the tooth to provide enhanced cleaning thereof. The second grouping contains a first subset of bristle tufts about the periphery of the second grouping acutely angled toward the toe of the toothbrush and a second subset bristle tufts acutely angled toward the handle of the toothbrush, which two subsets of bristle tufts are relatively less densely packed, for a combination of features which provides enhanced penetration of the interproximal spaces between the teeth during back and forth brushing of the facial and lingual tooth surfaces, a brushing method used by a significant percentage of users.
A second embodiment of the present invention comprises the two groupings of bristle tufts of the first embodiment, wherein in the second grouping the rows of bristle tufts are alternatingly longer and shorter, allowing each longer row to more deeply penetrate the interproximal spaces to reach and clean the tooth surfaces therein, without the interference of the adjacent rows abutting against the facial or lingual surfaces of the teeth, thereby enhancing the ability of the toothbrush to better conform to the curvature of the teeth for enhanced cleaning thereof.